Telephone system



J. L. McQUARRIE. TELEPHONE SYSTEM.

APPLICATION FILED DEC-27. 191s.

1,356,643, Patented Oct, 26,1920.

- station apparatus,

are effected at a selector switch for operat- In arrangements of this i invention,

the purpose of facilitating unirnn stares Parent o FicE.

JAMES L. lVIoQU'ARRIE, OF MONTCLAIR, N

' YORK.

JERSEY, ASSIGNOR TO- WESTERN EL'EC- TRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW T LEPHONE sYs'rEM.

Specification of Letters Patent. p t t t, 2 2

Application filed December 27, 1918'. Serial-No. 268,446.

To all whom it may concern: 7

Be it known that I, J AMES L. MoQUARRIE a citizen of the United States, residing at Montclair, in the countyof Essex, New Jersey, have invented certain new and useful Improvements in Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to automatic telephone exchange systems, and has particular reference to a circuit arrangement therefor. I

It has been customary in automatic systems of known construction to send impulses by interrupting the line circuit at the subwhereby circuit changes ing the same. character the possibility of an incorrect setting of the switch and consequent mutilation of a call is occasioned by accidental depression of the switchhook when removing the receiver therefrom, which results in an unintentional interruption of the line circuit and the transmission of a false impulse.

An object of the present invention is to provide vmeans whereby a will only respond to variations of current in the line circuit produced by the actuation of an impulse sending device, and which'will prevent operation of the switch should the line circuit be completely interrupted, as by an accidental depression of' the switchhook.

The inventive ideainvolved is capable of.

receiving a variety of expressions one the which, for the purpose vof illustrating drawing but it is to be that said drawing is. employed merely for the description of the invention as a whole, and not to define the limits thereof, reference appended claims for this purpose.

. The figure illustrates calling substation l1ne and'a' selector switch embodying the features of this invention.

v ,In the drawing,'thesubscriberssubstation apparatus A may be of the tion including the switchh ook which .is designed to close and interrupt the substation usual construcline circuit consisting of limbs 1 and 2. An impulse sending device B of any desired construction is also associated with the suband' includes a normally State of;

improvement in selector switch is shown in the accompanying expressly understood being had to the diagrammatically a eration of the sending device to shunt said apparatus. Another normally closed contact 4: is provided at the sending device B for bridging a resistance 5 in series with'the linecircuit. y I

A primary switch indicated at G and which maybe ofany known construction is employed for connecting the line circuit to' remain energized during the manipulation of j .80

the sending device, but relay 6 is soadjusted as to respond to the variations in current and willrelease each time resistance duced in the line circuit.

It is believed that theinvention will now be best understood through the following detailed descriptionof the operation." a When the subscriber at substation A.fre moves his receiver from its switchhook,"primary switch CV is operated in a manner well. known in the art to step its brushes onto the terminals of lector switch D. A.-circuit will then be j closed extending from grounded battery, left winding of marginalqrelay 6, left winding of relay 7, side switch wiper 8 in its first position, limb 1 of the subscribers line, substation apparatusfA, contact it and its associated spring, side switch wiper 9 in its first position, right winding of relay 7, and right winding of relay 6 to ground. .Relays .6 and '7 areenergizedand establish a'circuit for the slow-toereleas e relay. 10, extending from grounded battery, winding of said relaylO. front contact and armature of relay 6, front contact and armature of relay 7, tov ground. Relay 10in attracting its armature, pre- 5 is introsubstation A, and will release, should said line circuit. be inter-.

Upon manipulaa trunk leading to an idle separes a circuit for slow-.to-release relay 1 1 which is closed first lmnulse from sendlng deviceB;

upon transmission of the I by said device, contact 4 is opened, and the line circuit will extendthrough resistance 5. This change in current will not affect relay 7, as previously described, but the increase in resistance will cause relay 6 to re-v lease and slow-to-release relay 11 will immediately become energized over a circuit extending from grounded battery, winding of relay 11, front contact and inner armature of relay 10, back contact and armature of relay 6, front contact and armature of relay 7, to ground. Relays 10 and 11 remain energized during the transmission of impulses. A circuit will also be closed for primary stepping magnet 12 extending from grounded battery, winding of said magnet, side switch wiper 13 in its first position, front contact and inner armature of 'relay 10, back contact and armature of re- 1ay6, front contact and armature of relay 7, to ground. Stepping magnet 12 will continue to operate in response to impulses transmitted and thus step the brushes of selector switch A to the desired group of terminals. On the first step of switch D oifnormal contact 14 is closed. Energization of slow-to-release relay 11 operates escape magnet 15 over a circuit extending from groundedbattery, winding of said magnet, s1de switch wiper 16 1n its first positlon,

front contact and armature of relay 11, to ground.

At the termination of the first set of impulses, contact 4 will close and short circuit resistance 5 and relays 6 and 7 will both remain energized. This condition of relay 6 will break the circuit for slow-to-release relay 11 at the back contact of the armature of said relay 6, and upon deenergization of relay 11,'escape magnet 15 will release and cause the side switch wipers to move into their second positions. secondary stepping magnet 17 is immediately established which extends from grounded battery, winding of magnet 17, armature and back contact thereof, side switch wiper 18 in its second position, back contact and armature of escape magnet 15, to ground. Magnet 17, being self-interrupting, will step the brushes of switch D in their trunk hunting operation; The idle which brushes of the switch pass is denoted by ground, and upon being stepped onto the test terminal having such condition, a cir-' cuit will be closed for escape magnet 15,

'extending from grounded battery,winding of said magnet, side switch wiper 16 inits second position, test brush 19 and its associated terminal, to ground at the next succeeding selector switch (not shown). En

ergizationof magnet 15. breaks the circuit for steppingmagnet 17 and the brushes of the switch will come to rest upon the set of terminals leading to the idle selector.

A circuit for the The several side switch wipers are also moved to their third positions upon energization of escape magnet 15, thus causing the line circuit to be extended to the next selector and relays 6 and 7 to release. The sending device B may now be again operated and in accordance with any well-known practice the connection between the substation A and a called line willbe established.

If, before the sending device B is initially manipulated to operate selector switch D, the switchhook at substation apparatus A should be accidentally depressed, it will be apparent that the line circuit will be completely interrupted and relays 6 and 7 will both release. Consequently any false impulse, due to such depression of the. switchhook which would otherwise be transmitted to the selector switch, will be prevented froi so doing. 1

Should the subscriber at substationA replace his receiver before the side switch wipers of selector D have moved into their third positions, relays 6 and 7 will again release and a circuit will thereby be establishedfor release magnet 20, extending from grounded battery, winding of said magnet, off-normal contact 14, side switch wiper 21 in its first or second positions, back contact and outer armature of slow-to-ree lease relay 10 which becomes deenergized when relay 7 releases, back contact and armature of'relay 7, to ground. Upon energization of release magnet 20 a holdingcircuit is also established therefor, extendin from rounded batter I windin of said 7 magnet, ofi'-- normal contact 14, armature and front contact of magnet 20, to ground,

. and said magnet continues to operate to return switch D to normal position, whereupon the holding circuit for magnet 20 is said test terminal. The previously described holding circuit for release magnet 20 will also beestabli'shed, and brushes of'the switch and side switch wipers will be returned to normal. hen side switch wiper 22 returns to its first position, a ground will be fount which may be utilized for releasing primary switch C and which extends through the-12E armature of relay 7 back contact thereof, outer armature and back contact of 'relay 10, and side switch wiper 22 in its first position. This-ground is also employed to indicate the idle condition of'selector switch D after the same has been returned to normal.

What is claimed is:

In a telephone exchange system a calling line, a called line, a selector switch {or extending said calling line toward said called line, primary and secondary 'steppingmagnets for said switch, an escape magnet for controlling the operation of said secondary magnet, a release magnet for said switch,

two devices for changing the electrical con- 7 dition of said calling line, and electromagnetic means under the sole control of onev In witness whereof, ."I hereunto subscribe my name this 24th day of December A. D., 1918.

l JAMES L. MQQUARRIE. 

